Posts tagged ‘XForms’

The answer is simple: eXist Solutions (the company behind eXist-db) and betterFORM have joined forces to integrate their two long-standing projects and offer commercial support for this new platform. As true Open Sourcers we’ll continue to offer this new product as free, Open Source software. Not much change here. But additionally there now will be subscription-based support for those that need long-term reliability for their commercial applications.

Beyond having integrated our products to work seamlessly with each other we have also joined our skill set and experience in the XML domain. We offer this joint expertise to our customers as consulting, development and training services to enable them to build better applications in less time.

Share this:

Like this:

Model Item Properties (MIPs) are one of the central features of XForms. In short they allow to add constraints to XML nodes. The available MIPs are:

readonly – boolean XPath expression

required – boolean XPath expression

calculate – XPath expression

relevant – boolean XPath expression

constraint – boolean XPath expression

type – XML Schema simple datatype or extension thereof

However with XForms 1.1 each of these MIPs were allowed to be attached to a node only once. If a bind element happened to attach one MIP to same node a second time the processor would throw a XFormsBindingException.

This was rather limiting expecially with respect to the ‘constraint’ MIP as in practice it often happens that you’d like to test for more than one condition. Of course you can combine conditions with a simple ‘and’ like so:

<xf:bind nodeset="a" constraint=". &gt; 5 and . &lt; 10" />

But this leads to long and hard to read expressions. Wouldn’t it be much nicer to be able to write:

MIPs in XForms 2.0…

This is exactly what is addressed in the upcoming XForms 2.0. It now allows that one and the same MIP is attached to the same node several time and defines some combination rules. This table was taken from the current XForms 2.0 Draft.

property

combination

type*

all

constraint

all

relevant

all

required

one

readonly

one

calculate

not allowed

p3ptype

not allowed

*To be honest we still couldn’t make much sense out of the fact that the ‘type’ MIP is also allowed to be combined as the use cases seem to be rather exotic. But probably it just lacks a good example. For the time being we haven’t considered that in our implementation.

‘all’ means that all conditions are chained with a boolean ‘and’ so all conditions must become true for the constraint validation to become true. ‘one’ on the other hand combines the statement with boolean ‘or’.

…and beyond

The combination rules for ‘constraint’, ‘relevant’, ‘required’ and ‘readonly’ are now implemented in betterFORM. But we went some steps further and also picked up some of the ideas from a post published under the name ‘MIP Names, Type, Etc.’ on the W3C XForms group wiki.

Besides using the syntax shown above you are now able to write the following statements:

Here we find our good old friend the ‘alert’ element which XForms authors know as one of the child elements of XForms controls to signal an error. The alerts are now attached to a single constraint MIP and allow to tell the user exactly which of multiple constraints has failed in a given situation.

But there’s even more. In some situations even a single condition might be complicated and therefore hard to read. This is especially true when it’s crammed into an attribute. Now you can also write:

One Question left

Great, now we have the ability to signal to the user what exactly went wrong, combine several occurrences of a MIP and we can trigger each UI control bound to that node. But what if we do not want that? It might be even confusing if alert messages pop up in the UI at several places.

So we need a mechanism to selectively and explicitly say that we want an error to be displayed for a given control. We currently solved this like so:

‘srcBind’ is an idref and points to an existing bind with id=’aBind’. This is taken as the root element for all alerts that might be displayed (if their respective constraint fails) or not displayed (if their respective constraint passes). The xf:alert in the UI becomes a container for all messages whose constraint fails and are displayed as a stack.

We hope these extensions are useful and welcome your feedback.

Share this:

Like this:

A while back the XForms Working Group proposed to use @ref Attribute everywhere in XForms and replace all usages of @nodeset. We have followed this proposal and implemented this in betterFORM 5 development branch. This means that you don’t have to think any more which attribute (@ref or @nodeset) is right for the given element.

As a consequence the following elements now also accept @ref:

bind

header

itemset

insert

delete

repeat + repeat-ref

We appreciate this simplification and hope it helps avoiding authoring errors. Of course old forms that use @nodeset will continue to work.

Like this:

When building applications with many forms and especially when using a lot of subforms you’re often facing a lot of markup redundancy. This article shows a new utility in betterFORM to avoid such redundant parts thereby making your applications more maintainable.

In the XML world there is the well-known XInclude specification that handles includes in the XML markup language. However this specification only handles very simple file inclusions. If you have more fine-grained snippets to assemble you have to go for XPointer in addition which has unfortunately some shortcomings – it’s simply not or only partly implemented in many environments and has a somewhat crude syntax.

This article shows a more pragmatic approach which has been developed by the betterFORM team during its work on a large customer project.

To reference the “b-contact” bind in your form simply use the fragment identifier on the URI: <bf:include src=”templates/binds.xml#b-contacts />.

This technique already allows to group similar contents together in one file but to use them in different contexts.

Form authors will quickly see how useful this small extension is, but they will also notice that in the real world things are often not as easy as this. Consider example 3.

Example 3 – add some markup to the inclusion

Often when building large form applications with XForms you’re facing markup that is largely the same in different contexts. This is especially true with many submissions that load the same data in different parts of the application. But you have to repeat the whole block just to add a different a different error-handler as the message in the example below:

Please note the bf:action attribute here. This tells the engine to append the xf:message element to the included submission with id=”s-load-data”.

Extend Included Markup

Markup included via bf:include can easily be extended using the bf:action attribute. Example 4 shows how the bf:action attribute value “append” is used to chain a submission transforming the instance data to the “s-load-data” submission.

Overwrite Included Markup

Another scenario that comes up quite often is that a single piece of the included markup must be overwritten with some other markup. Example 5 shows how this can be achieved. Here the error message from example 3 is overwritten with another error submission handler:

It should be noted that this inclusion mechanism can be applied at deploy- or runtime. If you want to apply inclusions at runtime you have to configure betterFORM to do so by editing the betterform-config.xml file and setting the property “webprocessor.doIncludes” to “true”.

Conclusion

No question bf:include especially in combination with the XForms subforms mechanism is a powerful technique for form authors when writing maintainable enterprise applications. The bf:action attributes will be available in the upcoming betterFORM 5 release. If you can’t wait simply check out the betterFORM development branch at https://github.com/betterFORM/betterFORM/tree/development and get started.

Note: the inclusion is currently still not yet integrated within the build process of betterFORM. This will follow at a later stage.

Share this:

Like this:

Release Notes for betterFORM limeGreen 4.1

Changes

Installer

The targets of the installer have been renamed to represent the recent name changes on the betterForm website: betterFORM XRX has become betterFORM XML Suite and the “pure” betterFORM standalone/WAR can now be found as XForms Toolkit

Fixed Issues

Release Notes for betterFORM limeGreen 4.0

New features

Event Log

In previous versions of betterFORM event logging was available on the Firebug console (or its respective counterparts in Chrome and Safari). However this worked only for the uncompressed version of betterFORM as it relied on the console.debug feature of those tools.

In betterFORM limeGreen 4.0 there is a new event log that helps tracking the events exchanged between browser and XForms processor on the server regardless of the mode of operation. It is enabled by configuring the debug option in betterform-config.xml like this:

When active there will be a small icon in the upper right of the browser window. Clicking on that will reveal the event log.

In the event log each event that is received from the server will be listed with all of its context information. In some cases where an targetElement or targetId is given you can click on a link and the respective element in the browser will be highlighted in blue.

The icon in the upper right will allow to expand or collapse the event log while the trash bin icon allows to remove all entries from the log.

Error Highlighting

One of the most common errors when authoring forms is to produce a xforms-binding-exception. In complex forms these can be hard to locate. The new error highlighting feature improves this by giving you the exact line in your markup where your binding exception occurs.

In addition to the markup the requested URL and the exact XPath for the problematic element is shown.

Syntax Highlighting for Host and Instance Documents

The debug bar has been enhanced to now show the host and instance documents syntax highlighted too. Here’s an example:

Configurable Position for Ephemeral Messages

betterFORM uses a Dojox toaster control for displaying ephemeral message. These were always shown at the bottom of the screen. The position for these messages is now configurable by adding an attribute to the root node of the document:

The toaster position now can be any of the four corners of the browser window. Valid values for the attribute ‘bf:toaster-position’ are documented in the Dojo docs.

Automated Web Tests

Not strictly a new feature but we have started to automate cross-browser testing by using the new Selenium webdriver. We have already implemented a lot of tests which are now run twice a day to reveal potential regression bugs. The test assertions will be expressed in an XML format to ease the implementation of tests. From these definitions the Java code for Selenium will be generated. The tests may then be run against different browsers. We will continue to add tests and probably make the testing infrastructure available for developers that like to do their own tests.

Moved to Less for CSS Styling

LESS has a growing popularity for doing complex CSS layouts. Check out their website for an overview of the features. We decided to move all relevant CSS stylesheets to LESS as it is much more expressive than CSS and e.g. allows variables to avoid redundancies. LESS files get compiled into standard CSS so there are new dependencies at runtime nor restrictions on the use of ‘normal’ CSS files.

XForms Editor Preview

Starting with RC 2 there will be a new XForms editor in betterFORM. It will be (not in the first place) wysiwyg page editor but a pure XForms 1.1 editor which allows to edit all XForms markup contained in some (X)HTML document. It focusses on the abstract view of XForms authoring and assists to keep your markup clean and consistent. Large parts of the editor are generated directly from the XForms 1.1 schema thus supporting the full set of XForms elements and attributes plus the XML Events schema.

The first version will give access to the complete XForms language vocabulary unfiltered and will mainly target more experienced XForms authors. Starting from there ‘profiles’ will allow to filter and change the representation of the attribute editors and add authoring convenience functions.

After ‘expert mode’ (above) a ‘basic mode’ is planned as an alternative view for non-XForms users. This will works with implicit instances (instance nodes created on the fly) and smart defaults for quick editing without all the rarely used features.

What’s already working:

parsing of any XHTML/XForms document and opening it in the editor. Only XForms markup will be shown.

expandable/collapsible (tree-like) view of the XForms markup

schema-aware sidebar that shows only possible children and siblings for a given element

schema-aware dnd – still a bit quirky but allows to move elements in the tree

‘attribute panes’ with all possible attributes of a given XForms element which update the markup tree

inserting and deleting of all XForms elements

serializing changes

applying changes to original input document

preview, save + save as

We hope to create a tool for XForms authors to create fully valid XForms documents and appreciate all comments and suggestions. Contributors welcome.

ProjectAssistant

To simplify the setup of projects using betterFORM XRX there’s a new helper build tool called ‘ProjectAssistant’. It helps to keep your project sources separate from the betterFORM sources while still giving access to the full functionality of the complete source tree. It also allows to easily switch to a newer version of betterFORM as soon as it becomes available.

Windows Installer

There is a new Windows installer packaged as an .exe file to make installation for Windows users even easier.

Single-jar deployment

Starting with Release Candidate 2 betterFORM will default to using a single-jar deployment. This means that all Java classes plus all the needed resources (CSS, js, image and xsl files) will be packaged in a single-jar file that can easily be added to a web application. The jar will contain an optimized version of the JavaScript used in betterFORM and the overall size of the archive will be about 2.7 megs.

A new resource handler allows to turn caching on and off.

betterFORM XRX extension for eXist

We are very happy to announce that we now have a tight cooperation with the eXist project and directly commit the XRX extension to the eXist trunk. However we will continue to offer our own eXist/betterFORM bundle as a ready-made installer packed with the latest stable version of eXist.

One hotspot of our activities was to refine the eXist integration and to fix the issues that existed in the former release. There were some inconsistencies and shortcomings of that release and we think we have finally sorted those out. Configuration and installation should now be smooth.

We also concentrated on making the betterFORM extension a good starting point for building XRX applications that are stored completely in the database. There also will be a browsing tool that lets you browse, execute and view the sources of all of your app files. Additionally you can upload files to the database and create new collections as needed.

Dashboard

The betterFORM Dashboard is the new starting point when working with betterFORM. It replaces the simple form.jsp of former versions and allows to mange your XForms documents along with their resources (CSS, images, static HTML, JavaScript) in one place. Dashboard works on both pure webapps with filesystem storage or as collection browser for a XRX application on eXistDB.

Dashboard supports the XML application developer and XForms author in working with their resources. It lets you browse the hierarchical structure of your applications, create new collections, upload files and view the source-code. It will also allow to start the XForms editor with an additional button.

Dojo Upgrade

Dojo 1.6 is now integrated. All Dojo themes (tundra, soria, nihil and claro) can now be used in the forms.

Finer grained Dojo builds

There are finer grained Dojo profiles now for building optimized JavaScript files to reduce the size and amount of downloaded resources. Besides a minimal, medium and full profile it’s now also possible to build optimized JavaScript files for a specific page.

Attribute Value Tempate (AVT) support

AVTs are now fully supported on foreign elements (typically HTML). That means you can use XPath expression in any HTML attribute for instance will evaluate the XPath according to the XForms in-scope context rules allowing you to manipulate the rendering of HTML from XForms.

New Submission modes

There are two new submission modes:

a submission @replace=”embedHTML” now allows to embed HTML markup in your current document. You typically might want to use that to call some URL that produces HTML markup by templating (e.g. long output tables to display data). HTML can also be embedded by using a xf:load action but a submission gives you finer-grained control of your request (sending data if needed, validated or not, setting headers, error-handling etc.)

a submission @replace=”new” allows to open the result of a submission in a new window. Please note that this functionality has been accepted by the XForms WG as a new feature though with a different syntax. We’ll adapt to that syntax in a later release. Typical use case is the display of printable views.

XPath Functions

The Java classes implementing the XPath functions for XForms have substantially been refactored for easier extensibility. This is an important preparation for allowing users again to configure a new Java function library.

dispatch action supports custom contextinfo

The dispatch action now can take custom contextinfo. This is useful in context with subforms when single values shall be exchanged between models. An example illustrates that best. Assuming the action below is in scope of model A it may send either a static value or a pointer to an instance node value to model B with:

Context connector

There is a new connector with the scheme ‘context:’ that allows to store an instance into a hashmap of the XForms processor. This is a handy feature when composing wizard-style forms that are made of subforms and need to pass instance data back and forth. As the same XForms processor instance will be used over the live-time of the embedding document this can act as a global data-container for subforms.

SSL handling

SSL handling has been refined allowing a pluggable SocketFactory to be used. Details of the keystore can be configured in betterform-config and a howto has been added to the docs.

Multiple Labels

A control now may have multiple labels for different languages. This gives an easy alternative for quickly internationalizing forms. It’s planned to extend that approach for alerts.

Event reduction

The amount of events propagated to the client have been reduced dramatically. From now on only events that really have been used in a form will be propagated over the net.

XForms Inspector

There already was a feature allowing to view XForms instances at runtime in a Firebug console. But the solution had some shortcomings:

you needed to run on Firefox with Firebug plugin to see the instances

it was not obvious to users that you had to add a ‘?debug’ to the form URI to get the buttons

and worst it did not show the instances of embedded models as these could change at runtime

The new solution still requires that you activate the ‘debug’ feature in the betterform-config.xml but is now independent of Firefox and Firebug. Once activated a bar is rendered at the bottom containing one link to see the host DOM as it exists on the server (pre-transform) as well as one link for each instance in each model. The links update if a model becomes available by embedding or is removed from the document by unloading.

The XForms inspector can now be collapsed to an icon to avoid hiding elements on the page.

XForms Dialog

we now implement the proposal for the dialog element along with its show and hide actions.

XFormsPostServlet

There is a new XFormsPostServlet to allow initialization of a XForms from a http POST containing xforms markup in the body.

XForms Feature Explorer / Reference

The XForms Feature Explorer serves as a live reference for XForms and betterFORM. It has been completely overhauled and given a clean structure with description (with spec links), live example and source code. Alongside of that you will see which CSS classes that apply in the respective context and can even see them at work when hovering the class name. New sample forms have been added beyond the basic control and container documentation.

Here is a screenshot of one reference form:

Automatic CSS import for subforms

CSS style rules that are present in a document that is embedded will now get imported into the embedding document. Currently only style elements are handled but this still allows usage of external CSS files by using the @import instruction.

Automatic JavaScript import for subforms

Similar to CSS resources JavaScript blocks and linked JavaScript files from the head of the embedded document can be imported in the embedding document.

Refined user agent configuration

The betterform-config.xml now allows to configure a new user agent along with its supporting Java class and a XSLT transform.

Resource pathes

The handling of resource pathes has been simplified. Instead of having multiple pathes for CSS, scripts etc. there’s now only one for the resource root dir which is configurable in betterform-config.xml.

Saxon upgrade

The XPath processor is now using Saxon 9.2.1.5.

Http Client update

The http client has been upgraded to latest version of HttpComponents (formely Apache Commons HttpClient).

Logging

Java code level logging has been refined in many areas now giving you more fine-grained control on the level of detail you’d like to log. Instead of just ‘debug’ we are now making use of the ‘trace’ level which produces much better readable output.

Configurable delay for incremental

Each control may now have an additional delay for the firing of incremental events. If delay is 0 there will be one event for each keypress while a control has focus. A bigger value will defer the firing for the specified time in milliseconds.

Refined alerts and hints

The default behavior for alerts and hints has been reworked. As the default now inline alerts and hints will be used. Hints will show when a control gets focus. Whenever a control gets invalid the alert will show in the same place as the hint (covering it). Alerts can be closed by clicking on them in case they cover other fields in a complex layout. The CSS for these child elements has been stabilized and works with horizontal and vertical layouts.

New alternative date control

There’s a new date control consisting of three dropdown controls instead of the datepicker popup.

Restructured XSLT transforms

The XSLT stylesheets responsible for the transformation from XForms to HTML have been completely overhauled for easier maintainability and extensibility. The base stylesheet now again produces native controls which can be overwritten to add functionality like scripting. As a result the overall stylesheets are more modular, smaller and easier to enhance.

Fixed Issues

fixed various problems with stale UI Events leading to repeating alert messages in the browser

an issue with downloading of schemas from the internet has been fixed (Ticket #40)

a hard-to-catch race condition with the ajax calls was fixed that only shows under heavy test conditions. Now the client-side uses a fifo buffer to make sure all events are processed in right order and even is able to discard events that may have become irrelevant in the meantime through network delays.

the style attribute was not handled correctly in all places. This is fixed now. (Ticket #28)

some issues regarding focus events (especially group and repeat focus events) have been addressed.

fixed problem with setfocus action not setting the focus in some situations

enhanced error information for exceptions

upgraded to Xerces 2.11

fixed problem with JavaScript in model actions (Ticket #203)

fixed ranges within repeats (Ticket #201)

fixed missing support for choice labels (Ticket #195)

fixed problem with dependant lists in IE8 (Ticket #192)

fixed escaping problem with entities (Ticket #193)

fixed problem with params on instance @src attributes (Ticket #189)

fixed bug with positioning of tooltip alerts (Ticket #198)

added a TimePicker implementation (Ticket #178)

fixed issue with html default namespace

Besides the above dozens of smaller issues have been addressed. For a detailed list please visit https://betterform.de/trac/query?status=closed&milestone=limeGreen+RC4&group=status&order=priority or check the commit history on Github.

Share this:

Like this:

One area where we give ourselves in the hand of technology is air traffic. As soon as we enter an airplane we have to trust a complex machinery and hope that machines, pilots and ground personal are doing their job right and bring us safely back to the ground. But flying does not only involve airplanes and well-trained pilots but mountains of data about airports, airspaces, run ways, weather conditions etc. etc.

A important acronym in this domain is ATM which stands for ‘Air Traffic Management’. Two of the most important organizations in air traffic are the Federal Aviation Association (FAA) and Eurocontrol. Together both organizations developed a conceptual model of the whole aeronautical domain and also offer an implementation of that model in XML Schema. This is the technological foundation for Aeronautical Information Services (AIS) that allow the digital exchange of data between all relevant parties.

However it takes more than a schema to build an application. The schema describes all the entities, objects and their relationships and it’s up to the software vendors to build complete solutions from that. All the data that are needed to ensure a high level of safety in the operation of air traffic must be entered by humans and those need good user interfaces to do their job. The gathered information is then used on-flight to give pilots up-to-date information about outages, special conditions at certain airports, restricted airspaces and so forth.

This is where XForms comes into play. The aforementioned schema consists of about 4 megabytes of schema definitions and about 150 ‘features’ and same amount of ‘objects’ as they are called in this model. These ‘features’ and ‘objects’ can then be combined with each other, nested within each other and linked to other ‘features’ and ‘objects’. All this happens at runtime when ground operators build complex messages from the available set of entities.

Though clean from a conceptual view this highly dynamic model puts heavy burdens on the engineers and eliminates any possibility to build static user interfaces to support all types of messages. Fortunately the authors of XForms decided to build it upon XML and as such it is ideally suited to be generated from a formal description such as a XML Schema.

The application described here was build by a leading vendor of Air Traffic Control (ATC) solutions.Their engineers have choosen a SOA approach to provide maximum flexibility and connectivity with other applications. In the backend a large Oracle database is used to store all the collected data. The whole user interface for collecting and maintaining the data is generated from the XML Schema resulting in about 300 separate XForms documents using several dozens of custom datatypes. Each form comes with its own template instance which represents one entity from the schema. Those template instances are then aggregated at runtime to build a certain message to be stored in the database.

The necessary aggregation of instances and associated user interfaces was a problem that couldn’t be solved elegantly with XForms 1.1. The key to success was a tiny extension to XForms allowing forms to be embedded in already loaded ones. With an additional value ’embed’ for the attribute ‘show’ of the XForms load action and an attribute ‘targetid’ this extension is only a very small addition to the language set of XForms. Here’s an example:

This extension has already been proposed for XForms 2.0 which is currently under development.

Additional challenges had to be met: we needed a way to exchange instance data of a subform with their respective ‘master’ and to allow to ‘mount’ some piece of data into the master instance to build a complete messages. We developed several solutions to this that do not break the encapsulation of the target model but discussion of the details is left to another blog post. Further we had to find a user interface presentation that allows an operator to keep the overview over a complex document. To solve this we implemented a tabbed control behaving like a XForms repeat – for each loaded subform a tab is dynamically added and shows the respective subform within it. An additional breadcrumb navigation helps to keep track of the hierarchy in the document. Last but not least the instance data of a stored message are not allowed to contain empty nodes. Thus when loading a stored message for editing the data had to be merged with their template instances. This was solved with a XSLT transform to be executed whenever a message was read from the web-service layer of the database.

After heavy and serious testing the customer was able to deliver the first implementation of the standard worldwide which is now in production use in several countries. Soon after first release the generative approach proved itself valuable as the application needed to be migrated to a new XML Schema version. With a single excecution of the XForms generator the new forms were available and could be used right away.

We think this project is an impressive example of the power of XForms. To summarize the facts:

300 generated XForms documents

about 50 custom datatypes

a highly dynamic user interface embedded inside of a portal

about 4 megabyte of raw XML Schema data using about a dozen of different namespaces